do not allow script tags in description html

lib/tools.js

@@ -9,6 +9,7 @@ let jsdom = require('jsdom');
 let he = require('he');
 let _ = require('./translate')._;
 let util = require('util');
+let createDOMPurify = require('dompurify');
 
 let blockedUsers = ['abuse', 'admin', 'billing', 'compliance', 'devnull', 'dns', 'ftp', 'hostmaster', 'inoc', 'ispfeedback', 'ispsupport', 'listrequest', 'list', 'maildaemon', 'noc', 'noreply', 'noreply', 'null', 'phish', 'phishing', 'postmaster', 'privacy', 'registrar', 'root', 'security', 'spam', 'support', 'sysadmin', 'tech', 'undisclosedrecipients', 'unsubscribe', 'usenet', 'uucp', 'webmaster', 'www'];
 
@@ -23,6 +24,7 @@ module.exports = {
     formatMessage,
     getMessageLinks,
     prepareHtml,
+    purifyHTML,
     workers: new Set()
 };
 
@@ -232,3 +234,14 @@ function prepareHtml(html, callback) {
         return callback(null, juice(preparedHtml));
     });
 }
+
+function purifyHTML(html) {
+    let win = jsdom.jsdom('', {
+        features: {
+            FetchExternalResources: false, // disables resource loading over HTTP / filesystem
+            ProcessExternalResources: false // do not execute JS within script blocks
+        }
+    }).defaultView;
+    let DOMPurify = createDOMPurify(win);
+    return DOMPurify.sanitize(html);
+}